Furnace grate



Feb. 15, 1938. L, s'rElNMULLER l 2,108,394 l FURNACE GRATE Filed Nov.30, 1935 6 Sheets-Sheet 1 @s HVV. l.

Feb. 15, 1938. s'rElNMULLER 2,108,394

FIURNACE GRATE Filed Nov. so, 1955 6 sheets-sheet 2 Jazz-MA Feb. l5,1938. L. STE|NMULLER 2,108,394

FURNACE GRATE l Filed NOV. 30, 1935 6 Sheets-Sheet 3 mi v @al FURNACEGRATE Filed Nov. 3o, 1935 e sheets-sheen ifeb. 15, 1938.

IL. STEINMLLER FURNACE GRATE Filed Nov. 30, 1955 6 Sheets-Shed?. 6

Patented` Feb. 15, 1938 UNITED STATES PATENTv OFFICE ApplicationNovember so', 19`3'5, serial No. 52,423

' In Austria December 3, 1934 1oo1aim's.

"I'his invention relates to a horizontal grate, lthat is to a grate, thebars of which lie in one plane only. Such grates have hitherto been'useful only for relatively small outputs, so that their advantages couldonly be made full use of for small plants. As is to be expected suchgrate vconstructions are relatively primitively constructed'. Forinstance, the loosening ofthe fuel has only been effected with the aidof stirring implements operated by hand and consequently it was onlypossible to attend to relatively .small grates with such stirringimplements.

According to the invention a horizontal grate is provided which can beconstructed in any desired size and the charging and stirring of whichand the removal of ash is effected entirely automatically.

An essential'feature of the invention consists in this that the gratewhich is composed of a number of bundles of re bars disposedlongitudinally one behind the other is provided with one or more slicingand conveying rammers which, mechanically driven,v are arranged so as tobe capable of being reciprocated on or above the grate surfacelongitudinally of the same.

'I'he particular features of the drive, the shape andthe disposition ofthese rammers will be described in detail hereinafter.

A further feature of the invention is the peculiar arrangement of the rebars, which is such that alternate ire bars are stationary and capableof being'reciprocated. 'Ihe invention further relates to the manner inwhich the fuel is fed, the possibility of observing the fire duringoperation, the removal of the clinker, ash and the fuel which has notyet been burnt, and

' the supply ofrair under pressure to the grate and the accessibility ofthe grate. A further 40 advantage of the-grate construction according tothe invention' resides in this that the grate surface may withoutdiflculty be made of any desired length and also of any width throughthe-provision .of any number of separate grates 45 next to one another.When several grates are disposed next to one another the rammers arepreferably operated alternately or in opposite directions to oneanother, as in this way the uctuations in the air supply caused by thestirring are equalized and as uniform a combustion of the fire gases aspossible is obtained.

' The invention is described in detail in the following, description. ofa number of constructional examples which are illustrated in theaccompanying drawings in which- Figure 1 is a vertical longitudinalsection through the grate on line A-A of Figure 3,

Figure 2 is a vertical longitudinal section through the grate on lineB-B of Figure 3,

Figure 3 is a plan view of the grate surface, 5 only one half of thegrate being tted with re bars,-

Figure '4 is a vertical cross-section through the grate on line C-C ofFigure 3 to an enlarged scale,

Figure 5 is a vertical cross-section on line D-D of Figure 3 to anenlarged scale,

Figure 6 is a vertical longitudinal section at the chain with a rammerwhich is vertically adjustable,

Figure 'I shows another way of xing the rammer to a special chain link,

Figure 8 shows a diierent way of fixing the rammer to a special chainlink,

Figure 9 shows a cleaning device on the arrangement shown in Figure 8,

Figure 10 is a vertical longitudinal section through the front part ofthe grate with a cleaning device for the rammer and means for returningdropped fuel to the hopper.

In the constructionalexample shown in Figure 1 the grate is mounted in afurnace ue l. The grate is composed of frames 2 on which rest the firebars 3. Movable re bars 3a. and stationary re bars 3b are provided. Boththe stationary and the movable re bars are supported by the frames 2.The stationary fire bars are provided with downwardly directed lugs 4which embrace rotatably journalled bars 5. The bars 5 which arepreferably of square crosssection stand on edge when in the operativeposition (Figure 1), so that in conjunction with the peculiar shape ofthe downwardly directed lugs they prevent the re bars from being liftedoff. For preventing the movable ire bars 3a from being lifted off theframesv 2, the movable fire bars are provided at their forward end witha bottom projection 3c which engages under the frame 2 and are providedat the top with a projection 3d which engages over the corresponding- 45ly recessed rear end of the adjacent fire bar. At the frontend of thegrate all the re bars are provided at their forward end with a atdepression, `so that they engage under the front gratevplate. 'I'heframe itself rests on rollers 6 and has a reciprocating motion impartedto it by a toothed drive 1. The reciprocating motion' prevents the gapsbetween the re bars from becoming clogged up. causing them to be'con-ytinuously cleaned. This arrangement also pre- 55 vents cohesive cakes ofclinker forming on the grate surface. In the middle of the grate a chain8 is provided. This chain is acted on by driving means 9 which impart toit intermittently also a reciprocating motion. The chain carries arammer I which, as shown in Figure 1, extends transversely right acrossthe grate. The rammer I0 rests directly on the surface of the grate andis wedge-shaped. 'I'he rear surface Illa. of the rammer, which faces inthe direction of feed, is steeper than the front surface I0b which facestowards the front of the grate. At either side of the chain are cheeksII for guiding the chain. They prevent the chain coming in contactduring its to and fro motion with the re bars which are also in motion.These cheeks II are provided at either side with recesses IIa (seeFigure 4), for giving the combustlon air access both to the chain sideand to the re bar side. TheI chain itself runs oxi a longitudinal beamI2 which is also provided with recesses I2a for giving the air access.

The chain is driven by a driving mechanism disposed externally of thegrate, which may be so constructed through employing control levers andcouplings that the rammer can travel at different speeds along paths ofdifferent lengths on the grate. The 'driving mechanism may also be soconstructed that the chain continuously performs to and fro motions evenwhen the rammer is at rest. The object of this is to keep the air gapsbetween the chain and the side cheeks clean, just as in the case of thegrate, and to prevent lumps of clinker forming which adhere bring thechain to rest.

In the constructional form shown in Figure '7p the rammer is providedwith a projection Illa which engages in a correspondingly formed groove8b of the supporting chain member 8a, thus increasing the securityagainst lateral twisting. For the rest the rammer I0 is provided with alug Id which engages in a corresponding hole 8c in the chain member andis also pinned to the chain member.

For enabling the rammer to be easily adapted to the fuel or the load,that is, to make it possible to use another shape of rammer, 'the rammeris divided as shown in Figure 8. A support I3 extending the full widthof the-grate is used, over which plates I4 are pushed, which form therammer. 'I'hese plates can as required be slid ol sideways and bereplaced by plates of another shape, when the rammer has been brought infront of the fuel hopper. 'I'he support I3 is connected by a neck partI5 to a lug Ili which is insertedin the supporting chain member 8a. Asin this case the cleaning action of the plates I4 is not as great aswhen a continuous rammer is used, it is advisable to provide below thesupport I3 a separate cleaning device I3a in the form of wire brushes,scrapers and the like (Figure 9).

I The object, namely to have a somewhat raised rammer available for adeeper layer of fuel, may Y be fullled, as shown in Figure 6, byproviding a single rammer 20 which is vertically adjustable. This rammerhas its lower end 20a extending right through the chain. This lower endcarries a roller 2| which travels on a guiding rail 22.l

vide means for cooling the rammer.

For enabling the re to be kept under observation while in-operation, anobservation tube 26 is mounted in the hopper so as to extend through itslower end. For enabling the grate to b exposed from the front end, thelower part of the hopper is made so as to be capable of being hingedupwards. For this purpose the observation tube is also divided in such amanner that the forward half 26a' of the tube is mounted in the frontwall 25a of the hopper, while the rear half 26h of the observation tubeis xed to the rear wall 25h of the hopper. The front wall 25a of thehopper is arranged to hinge to the side like a door, while the rear wall25h of the hopper can be hinged upwards about a pivot 25e.

The lower end of the front wall 25a of the hopper is formed by a pivoteddoor 21 which can be swung upwards about the-pivot 21a. This takes placewhen the rammer I0 slides past below the lower edge of the pivoted door.In the example shown in Figures 1 and 2 the pivot 21a is disposed insidethe hopper.

In many cases it may be vof advantage to pro- This is effected as shownin Figure 10 by means of a water rosel3|l disposed in the vicinity ofthe front wall of the hopper.

The grate operates in the following manner:

During its operative motion towards the end of the grate the rammeralways pushes a portion of the fuel lying directly on the grate surfacetowards the rear, at the same time'sliding along under the fuel. At eachplace it thus only feeds the fuel lying there for a short distancetowards the rear, at the same time pushing it up on to its back. Thus atthe front end of the grate the fresh fuel is Aconveyed further towardsthe back, while towards the back end of the grate the rammer conveys thefuel that is burning there onwards and' at the far end of the gratepushes a portion of the clinker which is present there over the end ofthe grate into the ash pit. During its return motion how- .ever therammer, owing to the very slight inare provided which are fitted withconveyingrails 34 and are mechanically driven. In the con structionalexample which is intended for a furnace flue the entire grate with-theframe and the ash pit is enclosed in a trough 35, so that the bottom ofthe trough .at the same time forms the ash chute. For driving thereciprocating bar 34a a rack and pinion drive 36 or any other suitabledriving device may be employed.

The driving means just referred to also actuate conveying members 31cmbars 31a, which are disposed below the chain drive for the rammer orrammers (see Figure 4). These conveying members 31 with the conveyingbar 31a are disposed in a separate channel 38 which serves as acollecting space for the unburnt coal which is conveyed towards the backby the chain members. This channel 38 preferably opens (see Figure 10)at the front end of the grate into a separate collecting chamber 39 inwhich is mounted an upwardly leading conveyor device 40. 'I'he conveyordevice 40 conveys the fuel into a subsidiary hopper 4I disposed on thefront wall of the hopper 25, from where the fuel passes through thehopper back into the lire y space. 'I'he separate collecting chamber 39may be provided with a Water supply, so that the coal which isintermingled with glow- 4 resisting bodies 46 which on the outside areadapting embers can be quenched before `being returned to the hopper.

For making the grate suitable for a very high specific output means areprovided for the supply of air under pressure.- For this purpose anairbox 43 is provided below the grate, to which air is supplied underpressure by a blower. The airbox may be divided up by flaps 43a, throughthe opening and closing of which the grate, more particularly the grateend, can be cut off more or less from the supply of air under pressure.The supply of the air under pressure is effected at the front of thegrate from the side.

In order to prevent that too much air will pass through at the side ofthe grate, more particularly in the case of under-grate blast, airobstructing rails 44 are disposed on either side of the grate -(seeFigure 4), which are pressed by an elastic medium, for instance asbestoswool 45, against the fire bars. This also provides means for allowingfor the expansion of the iire bars when Ithey become heated.

The grate bed is bounded on either side by re ed to the shape of thefurnace flue. These bodies are not required in furnaces which are builtinto special re chambers, as in that case they are replaced by the sidewalls. It is also advisable to provide a fire resisting lining 4l at thefront end of the grate.

I claim:

1. In a furnace, a horizontal grate, a wedge shaped rammer extendingover the entire width of said grate, means comprising a continuousflexible band entirely below the plane of the grate surface forreciprocating said rammer longitudinally over the surface ofthe grate,the surface of the rammer directed toward the rear end of the gratebeing steeper than the surface directed toward the front of the grate.

2. The apparatus as claimed inclaim 1 in which the rammer consists of aplurality of parts, a transverse beam on which said parts are detachablyheld and means for connecting said beam'to the reciprocating means sothat it will move therewith.

3. The device as claimed in claim 1 in which theV means forreciprocating the rammer comprises a chain and a rail longitudinal ofthe furnace on which said chain travels, said rail being 'lovided with.lateral recesses for the supply of 4. In a furnace, a horizontal grate,a wedgeshaped rammer extending over the entire width of said grate,means for reciprocating said rammer longitudinally over the surface ofthe grate, the surface of the rammer directed toward the rear end of thegrate being steeper than the surface directed toward the front of thegrate, the means for reciprocating the rammer comprising a chain and arail longitudinal of the furnace on which said chain travels, said railbeing provided with lateral recesses for the supply of air, andstationary side cheeks are provided laterally of the chain said sidecheeks having recesses for supplying air to cool the chain and forauxiliary combustion air. f

5. The device as claimed in claim 1 in which a I water pipe is providedalong the front of the furnace and means for spraying water from saidpipe on the rammer.

6. In a furnace, a horizontal grate, a wedgeshaped rammer extending overthe entire width of Said grate, means for reciprocating Asaid rammerlongitudinally over the surface of the grate, the surface of the rammerdirected toward the rear end of the grate being steeper than the surfacedirected toward the front of the grate, and means for adjusting theheight of said rammer so that it cantravel either on the surface of saidgrate or at a distance above said surface.

7. An apparatus according to claim 6 in which the means for adjustingthe height of the rammer comprises a lug on the rammer extending throughthe reciprocatingmeans and a roller on the end of said lug, a guidingtrack on which said lug rests and means for vertically adjusting saidtrack.

8. In a furnace, a horizontal grate, a wedgeshaped rammer extending overthe entire width of said grate, means for reciprocating said rammerlongitudinally over the surface of the grate, the surface of the rammerdirected toward the rear end of the grate being steeper than the surfacedirected toward the front of the grate, means for adjusting the heightof said rammer so that it can travel either on the surface of said grateor at a distance above said surface, the means for adjusting the heightof the rammer comprising a lug on the rammer extending through thereciprocating means and a roller on the end of said lug, a guiding trackon which said lug rests and means for vertically adjusting said track,said last named means comprising a rod extending to the exterior of thefurnace, and levers connected to said track and operable by said rod.

9. 'I'he apparatus as claimed in claim 1 in which l the rammer consistsof a Aplurality of parts, a transverse beam on which said parts aredetachably held and means for connecting said beam to the reciprocatingmeans so that it will move therewith, and in which scrapers are attachedto said and the link to which the rammer is attached is' provided with alongitudinal groove and therammer is provided with a transverse ribengaging in said groove.

LEBRECHT s'rEmMImR.

